I was reading about the increasing scope of Jewish dietary restrictions in post-biblical antiquity (I think it was in Rugby League Week, or maybe 4x4 Magazine), as succeeding generations of Rabbinical scholarship interpreted Leviticus more and more expansively, and it occured to me that this is a classic example of an inherent problem with blacklists. Once you've committed to maintaining one, you've also implicitly conceeded that it's only going to grow larger over time.

Whatever problem you're trying to solve with a blacklist, be it the easy availability of pornography via the Internet (Back in my day, pornography was rare and expensive, and kids valued it accordingly, damn it!), the imagined presence of reds under the bed, the question of who should be allowed on a plane, or divining the will of Yahweh at mealtimes, at some point somebody sensible is going to observe that this is all getting a bit silly and unhelpful, and we really should have thought things through a bit more thoroughly before opting to go down this road.